Brush zucchini with olive oil and season with salt and pepper. Grill over medium heat in a grill pan until tender and marked. Allow to cool and dice.
In a 12-inch cast iron skillet, melt butter over medium-high heat. Add pancetta and cook until crisp. Add garlic and allow to cook until fragrant. Stir in the grilled zucchini, tomatoes, and fresh herbs. Slightly beat egg whites in a large bowl and add to the pan. Turn the heat off, stir in the Swiss cheese and season with coarse salt and 1 teaspoon of black pepper. Place in oven and bake for 25 to 30 minutes or until egg is set. Remove from the oven and serve.